Conventionally, as a liquid crystal display device using LEDs of three primary colors, R(red)-G(green)-B(blue), liquid crystal display devices of field sequential system (hereinafter, referred to as an FS system) have been implemented, for example, as disclosed in JP 2000-241811. In the FS-system liquid crystal display device, three-color LEDs are provided on the back surface of a liquid crystal shutter, each of the LEDs is sequentially lighted at high speed while opening and closing the liquid crystal shutter in each pixel position to be synchronized with lighting of the LEDs, and thereby, a desired color can be displayed in each pixel position.
For example, in the case of displaying red, the liquid crystal shutter is opened during a period of time a red LED emits light, and then closed during a period of time a green LED emits light and a period of time a blue LED emits light. The case of displaying green or blue is the same, and the liquid crystal shutter is opened only during a period of time the LED of desired color emits light, and closed during periods of time the other LEDs emit light.
Further, opening the liquid crystal shutter for periods during which red and green LEDs emit light enables Y (Yellow) to be displayed, opening the liquid crystal shutter for periods during which red and blue LEDs emit light enables M (Magenta) to be displayed, opening the liquid crystal shutter for periods during which green and blue LEDs emit light enables C (Cyan) to be displayed, and opening the liquid crystal shutter for all the periods during which red, green and blue LEDs emit light enables W (White) to be displayed.
In such an FS system, by lighting three-color LEDs sequentially at speed higher than human visual reaction speed, color display is implemented by additive color process. Then, adopting the FS system eliminates the need of color filter, and enables sharpened color display to be performed.
With the widespread use of portable devices such as cellular telephones in recent years, it has been desired to achieve display devices capable of being mounted on the portable devices and performing color display with high definition. The liquid crystal display device using three-color LEDs as described above does not need a color filter, and therefore, enables display with high luminance.
However, in the liquid crystal display device using three-color LEDs, a large number of LED chips are generally provided to constitute an LED of each color, the voltage is applied to the large number of LED chips to light the LED of each color, and therefore, power is consumed in the large number of LED chips.
Meanwhile, there are limitations in capacity of a battery in a portable device, and the less current consumption in a display device, the better. Obviously, reduction in current consumption is required of not only portable devices but also all the electric devices.
Further, LEDs have fluctuations in characteristics, and it is required to perform display with uniformity, while absorbing the fluctuations. In order to absorbing the fluctuations, methods have conventionally been used such that a fine adjustment is made to a resistance value corresponding to the LED of each color, but there is a problem that such operation requires significantly complicated effort.